A prerequisite for achieving high energy efficiency of water supply systems (understood as using less energy to perform the same task) is the appropriate selection of all elements and their rational use. Energy consumption in water supply systems (WSS) is closely connected with water demand. Especially in the case of oversized water supply systems for which consumers’ water demand is at least 50% less than previously planned and flow velocity in some parts of the system is below 0.01 m·s⁻¹, this problem of excessive energy consumption can be observed. In the literature, it is difficult to find descriptions and methods of energy management for such a case. The purpose of this study was both an evaluation of the current demand of an oversized WSS and a preliminary technical analysis of the possibility for energy saving. Solutions are presented that resulted in improvements in energy management, thus increasing energy efficiency. The conducted analyses indicate the wide use of numerical, hydraulic models, among others, for the needs of the sustainable oversize water supply systems management in order to improve energy efficiency. Those simulations only give energy consumption results as a first step in the process of decision-making for the modernization process, in which investment costs should be taken into account as a second step. Thus, this paper emphasizes the crucial role of hydraulic models as a good analytical tool used in decision support systems (DSS), especially for large, oversized water supply systems.

The article presents an integrated (inferential) system of computer assistance in waste management designed in component-based technology. The system allows for the implementation of individual elements (system components) with native and managed programming languages and performance technologies, ensuring easy integration of those components into one coherent, cooperating whole. One of the key issues involves the placement of the objects, events and conducted spatial (geographical) analyses in the system through the application of GIS technology (ability to use digital (vector or halftonebased) terrain maps), execution of spatial analyses, data visualization on maps, etc., using also commonly available spatial data available as part of the Infrastructure for Spatial Information (established under the Act on Infrastructure for Spatial Information).

In this paper, the results of cancer risk evaluation for chloroform in tap water at Cracow city (Poland) are presented. Cracow is a large city which is mostly supplied with surface water. The raw water seasonally has a high content of organic matter. Since chlorine is the basic disinfectant, organic compounds react with chlorine which results in the disinfection byproducts formation, such as trihalomethanes, in delivered water. Calculations were made, separately in male and female, for average chloroform concentration in the whole city as well as with respect to the season and supply zone. The study is based on the multipathway method which takes into account three ways in which chloroform contained in the tap water enters the human body (oral ingestion, dermal absorption, and inhalation exposure). The total cancer risk is at the acceptable level (between 10⁻⁶ and 10⁻⁵) because the chloroform concentration in water supply system only incidentally exceeds the maximum allowable concentration regulated by Polish Ministry of Health, i.e. 30 µg/L.

The main threat to human health is associated with organic compounds, which are found in the natural water ecosystem. The law relating to drinking water quality protects consumers’ health. Thus, the need to remove disinfection by-products (DBP) precursors requires the application of high-efficient water treatment processes. Usually, chlorine is used to disinfection, and then, haloforms are generated. Well-calibrated model, estimating the concentration of DBP in treated water, can be a useful tool for predicting the quantity of trihalomethanes in water in the distribution network. Such a model makes it also possible to identify the critical control points in the monitoring process. This paper presents the statistical analysis of chloroform formation in treated water, based on laboratory tests. The chloroform concentration is expressed as a function of factors, which determine kinetics of the chemical reaction of organic compounds with chlorine. Two new variables—the ratio of total organic carbon and chloroform and the ratio of chlorine consumption and chlorine dose, both obtained after 1 h of the reaction—were taken into account. From the function predicting the chloroform concentration, one can determine the optimal dose of chlorine in the disinfection of water in dynamic operational conditions.

The main purpose of presented study was to show the potential threat of the access to drinking water of uncertain quality. Protection against contamination of natural aquatic ecosystems is the main action taken to reduce the danger of different threats. The European Union using legislation, through issuing the Water Framework Directive, established a plan in the field of water policy, aiming at protecting groundwater better. The Directive orders each Member State to use water in a rational way and obliges them to protect the water resources in accordance with the principles of sustainable development. The target of this paper is to analyze the variability of nitrates concentration in water intended for Silesian inhabitants consumption in the period of 2008–2012. In research methodology, water supply systems were divided into categories, depending on the daily demand of water or alternatively on the number of settlement units supplied with water. This variable was connected with the amount of quality water control and the probability of exceeding the maximum permissible concentration of nitrates in drinking water. The areas with the highest risk of nitrates contamination in a tap water were defined using the land cover layer and nitrates concentration in surface raw water and drinking water.